The present invention relates to the production of liquid hydrocarbons and particularly to the production of heavy liquid hydrocarbons using various thermal methods. In particular, the invention relates to the production of liquid hydrocarbons utilizing steam to heat the formation containing the hydrocarbons. This method is especially adaptable to the recovery of heavy crude deposits.
The enhanced recovery of heavy crude deposits using various steam methods has become particularly attractive in recent years due to the increase in the price of crude oil. While the recovery of heavy crude deposits is economically viable, it is still a very expensive operation compared to other methods of recovering crude. The cost of generating the steam required for recovering the crude oil deposits accounts for a considerable percentage of the actual crude recovered. The process can require as much as one-third of the total crude oil recovered to produce the steam necessary for the recovery process. Thus, it is readily appreciated that any technique that permits the operator to utilize the steam more efficiently will produce large economic benefits.
In U.S. Pat. No. 4,581,926 there is disclosed a method for measuring both the quality and the quantity of steam being injected into a selected formation. Knowing the quality and quantity of the steam being injected into a selected formation the operator can adjust the quantity injected to provide the most efficient recovery of crude oil. The measurement of the quantity of steam injected into the various formations can be used to develop an injection profile for the well. The injection profile will allow the operator to quickly detect any problems with the well such as a breakthrough between the injection well and the producing well.
The apparatus disclosed in patent '926 utilizes a turbine wheel mounted on the shaft of a direct current permanent magnet motor/generator. The motor/generator is coupled to the surface by a suitable cable means so that current may be either supplied to the motor to drive it or to measure the current produced when it is operated as a generator. Utilizing these measurements, one can compute the torque versus speed curve produced by the motor generator. Using this data and the procedure described in the patent, one can determine the quality and quantity of steam being injected.
In U.S. Pat. No. 4,736,627 there is disclosed an improvement on the above described patent. In particular, this patent describes an apparatus utilizing a series of wire bristles to temporarily separate the liquid from the vapor in the steam. The bristles have a length greater than the radius of the borehole and are curved either in an upward or downward direction as the measuring tool carrying the bristles is lowered or raised in the borehole. The tangential contact between the bristles and the borehole wall tends to capture the liquid film that flows along the wall of the borehole and direct it inwardly toward the center of the measuring tool.